Speaking at the IFT show earlier this month, Dr Douglas Paddon Jones at the University of Texas medical branch, said: “If you put healthy people in their 70s* in bed for 10 days, they can lose 10 percent of their total lean leg mass. That’s a tremendous muscle loss.”
And younger people also lost surprising amounts of muscle after even short periods of enforced activity, said Paddon Jones, who has conducted several National Institutes of Health and NASA/National Space Biomedical Research Institute-supported bed-rest studies.
Sarcopenia – the loss of muscle mass associated with aging – did not happen smoothly and progressively, but could be represented by a downward curve punctuated by a series of sharp dips, he said.
“What you get is periods of very rapid muscle loss followed by partial recovery, which can turn a healthy 40-year-old into a frail 70 year old.”
‘We’re not advocating blindly throwing more protein into people’s diets’
Giving hospital patients more high-quality proteins with branched chain amino acids could help, he said. But there were also lessons to be learned about the day-to-day diets of people of all ages.
Critically, adding up the total amount of protein we eat per day was not a tremendously useful way of determining whether we are actually getting enough, he pointed out.
Indeed, many Americans consume more than enough protein, perhaps 90g a day, but pack nearly all of this into their evening meal, with perhaps 10g (or none at all) at breakfast, 15g at lunch and a whopping 65g at dinner, he said.
But as out bodies can only process around 30g at one sitting and turn it into muscle, there was little point wolfing down 50-60g in one meal, he pointed out.
Eat more protein at breakfast and lunch, and less at dinner
Meanwhile, eating a very small quantity of protein earlier on in the day wasn’t much use, added Dr Donald Layman, professor emeritus at the University of Illinois at Urbana-Champaign.
“If you’re eating less than 11g or so at breakfast, you’re not having an effect on protein synthesis: it’s just calories. Grazing all day with small amounts of protein is not great.”
Said Paddon Jones: “We’re not advocating blindly throwing more protein into people’s diets; in lots of cases we’d suggest reducing it, especially at evening meals.”
Ideally, he said, we should aim to consume up to 30g, three times a day. “We need to include more high-quality proteins at breakfast and lunch to maximize potential for muscle growth. We should consume moderate amounts three times a day in close proximity to physical activity, so you get the synergistic effects of exercise and protein.”
Talking to consumers about protein
Recent focus groups conducted by dairy industry-funded body Dairy Management suggested that consumers in the 45-65-year old age bracket responded best to messages connecting protein with mobility and independence, said director of new product insights Cara Kelly.
The most popular statement from a selection designed to encourage consumption of dairy protein was: “Protein from dairy helps to build and maintain the muscles that support your skeletal system and keep you mobile as you age.”
However, consumers also responded positively to statements pointing out that you could lose 1 percent of your muscle per year after the age of 40 – and that whey protein could help arrest this decline, she said.
Why does it matter if we lose muscle mass?
Significant loss of muscle mass often goes undetected as muscle is replaced by fat. However, it is a major health concern as populations age, reducing mobility, increasing the risk of falls and fractures, and reducing independence.
* Kortebein P, Ferrando A, Lombeida J, et al: Effect of 10 days of bed rest on skeletal muscle in healthy older adults. JAMA 2007;297:1772-1774; Paddon-Jones D, Sheffield-Moore M, Urban RJ, et al: Essential amino acid and carbohydrate supplementation ameliorates muscle protein loss in humans during 28 days bedrest. J Clin Endocrinol Metab 2004;89:4351-4358.